The ambivalent effect of Fe3O4 nanoparticles on the urea-induced unfolding and dilution-based refolding of lysozyme.

Due to the numerous biological applications of magnetite (Fe3O4) nanoparticles (MNPs), it is essential to identify the influence of these nanoparticles on basic biological processes. Therefore, in this research, the effect of MNPs on the structure and activity of hen egg white lysozyme (HEWL) (EC 3.2.1.1) as a model protein was examined using tryptophan intrinsic fluorescence, UV/Vis, and circular dichroism spectroscopy. Moreover, enzyme activities were analyzed by a turbidometric approach in the presence of MNPs at concentrations providing MNPs/HEWL ratios in the range of 0.04-1.25. As-synthesized MNPS were characterized by Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and the zeta potential of MNPs was measured to be -29 mV. The goal of this work was investigating the ordering or disordering effect of MNPs on protein structure at ratios lower or higher than 0.918 as concentration ratio of threshold (CRT), respectively, in order to answer the question: 'How can the denaturation and refolding of a model protein (HEWL) be affected by MNPs?' As has been reported recently, the protein folding, helicity, and half-life were improved at CRT to make the protein more disordered upon interaction with MNPs. The disordering effect of urea at >CRT and even at

L-arginine modified magnetic nanoparticles: green synthesis and characterization.

In recent years, there has been considerable interest in Arg which is a unique, nontoxic, and biocompatible biomolecule since it can be utilized as an agent for the functionalization and subsequent stabilization of MNPs against oxidation and aggregation, during or after a synthesis procedure. Our studies demonstrate that Arg has great impacts on MNPs with the decreasing size of the particle. Also, saturation magnetization and electrostatic interactions of RMNPs have a direct impact on biological molecules such as proteins and nucleic acids. By controlling the concentration of Arg, it is possible to accurately control the above-mentioned characteristics, which are useful tools for applications such as connecting to antibodies, catalysis, drug loading, and modification of MNP stability. In the current study, three RMNPs with different Arg densities, i.e. 0.42, 1.62, and 2.29 µg per mg were successfully synthesized through a simple co-precipitation method (named p 0.5, p 1, and p 1.5, respectively) and verified by colorimetric determination. Also, the as-synthesized RMNP powders were characterized by XRD, SEM/EDAX, FTIR, VSM, and zeta potential analysis. The presence of a magnetic core was proved by XRD, FTIR, and EDAX. Colorimetric analysis showed the existence of Arg in the synthesized samples. According to the zeta potential and VSM results, increasing the cap of Arg on the MNP surface leads to an increase in the surface charge and decrease in the magnetization of the RMNPs, respectively.

Effects of diode laser (980 nm) on orthodontic tooth movement and interleukin 6 levels in gingival crevicular fluid in female subjects.

The aim of this study was to evaluate the effects of low-level laser irradiation on the rate of orthodontic tooth movement (OTM) and the interleukin-6 (IL-6) concentration in gingival crevicular fluid (GCF) during orthodontic treatment. In this randomized split-mouth double blind clinical trial, 11 female patients aged 14 to 25 years (mean 19 ± 4.21 year), who required canine retraction following four first premolars extraction, were selected. The GaAlAs laser diode laser (A.R.C. Laser GmbH, Nürnberg, Germany) (980 nm, 100 mW, 5.6 J/cm2, three points from the buccal side and three from lingual side of the tooth, 56 s, running in continuous mode) was used for canine retraction in only one maxillary quadrant (LG). The irradiation time for each cervical and middle third of the tooth was 10 s, and 8 s for the apical third of the tooth. The other maxillary quadrant served as the control group (CG) using the laser pseudo-application in this side. The laser irradiation was applied on days 0, 7, 14, 21, and 28 of each month during the canine retraction phase. Canine retraction was done using closed coil spring with 150 g force on rectangular wires after the alignment and leveling. This study was done in 11 months. Dental casts were made at different time points during the treatment, and the amount of tooth movement was measured. To evaluate the levels of IL-6, GCF samples were collected from the distal side of the maxillary canine teeth on both quadrants at the beginning of the trial, the end of aligning phase, and on day 21 of each month during canine retraction. Although the mean rate of canine retraction was higher in the LG (0.013) than the CG (0.012) and there was definitely a tendency for more canine retraction in the LLLI, but the results failed to show any significant difference between the mean rate of canine retraction of both groups (P = 0.068). A paired t test showed that there was no significant difference in the mean concentration of IL-6 at various stages of the treatment between the groups during canine distalization (P > 0.05). Therefore, conclusive evidence could not be provided to support the efficacy of the diode laser (980 nm) in accelerating OTM in female subject.

Evaluation of the accuracy of panoramic radiography in linear measurements of the jaws.

BACKGROUND/OBJECTIVE: Panoramic radiography has a great place among imaging techniques because of its enormous advantages. One of the characteristics of an ideal imaging technique is to supply precise measurement. The purpose of the current study was to evaluate the accuracy of linear measurements of the jaws on panoramic radiographs. PATIENTS AND METHODS: In this study, the vertical distances between the metal markers were measured by panoramic radiography in seven sites of two skulls in various head positions. Then the radiographic measurements were compared with the actual values. RESULTS: Eighty three percent of the measurements were underestimated, 8.5% were overestimated on panoramic radiography and 8.5% of the measurements had no difference with the real measurements. Overestimation was not greater than 1 mm. The difference between actual and radiographic measurements was less in the posterior areas and in the mandible . In all head positions, the greatest difference between actual and radiographic measurements occurred in the anterior area. CONCLUSION: Based on the results of this study, linear measurements on panoramic radiography are more reliable in the posterior areas and may be used in early clinical measurements.

Dental age assessment among Iranian children aged 6-13 years using the Demirjian method.

BACKGROUND: Many methods of age estimation have been suggested, and of these, the Demirjian method is the most frequently used. The objective of the present study is to test the accuracy of the Demirjian method for age estimation in an Iranian population. MATERIALS AND METHODS: A cross-sectional study involving 141 boys and 170 girls selected by a convenience sampling method was carried out. Panoramic radiography was used to score the left mandibular teeth and to obtain the Demirjian tooth age. RESULTS: The Demirjian method overestimated the age of boys by 0.34 years and girls by 0.25 years. The scatter plots showing the difference between estimated dental age and chronological age for boys and girls showed that the regression lines had a decreasing trend with age. The mean difference between estimated dental age and chronological age in boys decreased with age (except in the oldest age group of boys). In contrast, it increased in girls between the ages of 6-8 years old, and then decreased. CONCLUSION: The results show that the Demirjian method is appropriate for estimating the dental age of patients, especially those belonging to the 9-13 year old age group. However, in the younger age groups, further study involving more cases is required.

Panoramic-based mandibular indices and bone mineral density of femoral neck and lumbar vertebrae in women.

OBJECTIVE: The aim of this cross-sectional analytic study was to evaluate the diagnostic efficacy of panoramic-based indices of the mandible (Mental Index-MI, Mandibular Cortical Index-MCI and Panoramic Mandibular Index-PMI) and to determine their correlation with bone mineral density (BMD) of the femoral neck and lumbar vertebrae (L2-L4) in order to assess the possibility of using these parameters as indicators of osteoporosis. MATERIALS AND METHODS: The mandibular indices of 67 women over 35 years old were measured from panoramic radiographs, and bone densitometry was performed in the femoral neck and lumbar vertebrae (L2-L4), using DXA (Dual Energy X-ray Absorptiometry) technique. The patients were divided into three categories of normal, osteopenic and osteoporotic in each skeletal region. One-way ANOVA and ROC curve analyses were applied. The results were considered statistically significant when the P-value was less than 0.05. RESULTS: Comparing the mean BMD in the femoral neck in women between C1 and C3 subgroups of MCI, a significant difference was detected (P=0.04). The mean PMI in the three skeletal subgroups was not different according to the skeletal region (P>0.05). We found a significant difference in mean MI between normal and osteopenic subgroups in the femoral neck (P=0.042). CONCLUSION: Using radiomorphometric indices of the mandible (MCI-MI) may be useful in determining the skeletal status of the patients, but is not sufficient for precise evaluation.